<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <p>苹果<i>{{qian}}</i>元一斤，打{{breaks}}折</p>
        <i>输入你要购买的斤数:</i><input type="text" v-model="num">
        <button @click="buy">结账买单</button>
        <div><p>总价：<span>{{total}}</span>元 <i>||</i> 折后价：<span>{{discount}}</span>元 <i>||</i> 省了<span>{{save}}</span>元 </p></div>
    </div>


  <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
  <script>
    const app = new Vue({
        el:'#app',
        data:{
            qian:10, //多少元一斤
            breaks:8, // 打几折
            num : 0, // 斤数
            total:0,  // 总价
            discount:0, // 折后价
            save:0   //省了多少钱
        },
        methods:{
            buy() {
                this.total = this.num * this.qian
                this.discount = this.total *(this.breaks / 10)
                this.save = this.total - this.discount
            }
        },
       
        
    })
  </script>

    
</body>
</html>